The groups that were involved in this event were the terrorist group known as al-Qaeda and the United States. The terrorists held planned four attacks on the US on September 11, 2001. They planned to attack the Twin Towers in NYC and the pentagon in Washington D.C. or specifically Arlington County, Virginia.
9/11
On September 11, 2001, terrorists associated with the Islamic extremist group al-Qaeda hijacked four airplanes and carried out suicide attacks against the United States. Two of the planes were flown into the towers of the World Trade Center in New York City. A third plane hit the Pentagon just outside Washington, D.C. The fourth airplane crashed in a field in Pennsylvania after the passengers of the plane took the plane back from the Islamic extremists. "The decade after the 9/11 attacks reshaped many facets of life in America." Jason Villemez writor for PBS.com.
Causes
This tragic event occurred because of a few reasons. One reason is that the extremists associated with al-Qaeda retaliated against the United States because of the American support for Israel. The terrorists also retaliated because the US was involved in the Persian Gulf War. The Islamic extremists were also angry because of the United States' continued military presence in the Middle East.
long term effects
One effect of the attacks on 9/11 is the death and destruction that was caused, 343 firefighters and about 3,000 people died in the attacks. The damage to New York City was billions of dollars. This event also instilled a sense of concern for our safety, this was the first time in recent years the US has been attacked on its own soil. New restrictions and regulations on air travel were issued after this event in hopes of making this country safer. The government also created the US Patriot Act which is an act of congress that stands for Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001. Another effect of 9/11 was the immigration and tourism rate of the US, the years following 9/11 the immigration/tourism rates lowered because of fear. Another effect is the American Muslim hate/fear. Because of the horrible incidents on 9/11 it has become "normal" to be scared of Muslim or Islamic people even though they personally have not done anything wrong. The last effect of 9/11 is the war against terrorism. Ever since this attack the US has been fighting in the Middle East against the war on Terror and this war will most likely not stop anytime soon. Especially with the new terrorist group ISIS threatening the safety of the United States.
9/11 attacks on the World trade Center in New York City